Embodiments of the method disclosed regard use of a torque sensor (e.g., transducer) and using the measured torque to detect the different fluid and mixing properties, conditions, and abnormalities in a mixing process. The torque produced in the mixing process relates to different fluid properties such as viscosity and density. It also relates to different mixing conditions such as presence of obstacles and changes or issues with gas sparging. Moreover, torque measurements enable determination of power transmitted to fluid by actual measurement, in contrast to using solely empirical impeller power number and speed, and allowing for actual mass transfer determination (i.e., gas transfer calculations).